| 摘要 |
A technique for decoding an encoded data stream representing an original sequence of data bits is provided, wherein the encoded data stream comprises a plurality of codes, each code being dependent on a current data bit and a first predetermined number of preceding data bits in the original sequence. For each of a number of possible states of the first predetermined number of preceding data bits, a score is provided indicating the likelihood that the corresponding state represents the first predetermined number of preceding data bits. The scores are arranged in an initial ordering. Upon receipt of a code given each of the two possible values of the current data bit in the received code, two update values are determined for each state indicating the likelihood, based on the received code, that that state represents the first predetermined number of bits. A first plurality of score bit slices are stored to collectively represent the initially ordered scores, each score bit slice containing a predetermined bit from each of the scores. The scores are then reordered and a second plurality of score bit slices are stored to collectively represent the reordered scores. From the update values, a first plurality of update bit slices for the first plurality of score bit slices and a second plurality of update bit slices for the second plurality of score bit slices are generated. Then, a first candidate plurality of updated score bit slices are generated from the first plurality of score bit slices and the first plurality of update bit slices, and a second candidate plurality of updated score bit slices are generated from the second plurality of score bit slices and the second plurality of update bit slices. Finally, a plurality of updated score bit slices is generated by, for each score represented by the bit slices, applying predetermined criteria to select the bits for that score from either the first candidate or the second candidate plurality of updated score bit slices. By this approach, all the scores are updated simultaneously.
|
